Itch can host digital files. That can be comics in the usual comic book reader formats. PDF is not especially suited for this, but many use it anyway. There are comic book readers that use more suited formats. But those are usually just zip files with a special file ending and conventions how to name the files inside the archive.
Using Itch as a online display for a comic series is tricky. Itch offers not really much help there. Just like you could upload a movie here, but there is no video player, unlike a specialized site like Youtube.
Webcomic series are ususally hosted on the site of the developer. Itch is not suited for frequent updates of comic strips. Hosting archived versions of a series is more suited to Itch.